1. Field of Invention
The invention relates to a dual sensor encoder system that compensates for eccentricity errors that may be introduced during mounting. The dual sensor encoder system may be used to control positioning of a printing drum architecture.
2. Description of Related Art
Printing drum architectures require precise rotational alignment signaling to accurately align and time paper transport and image generation. This is particularly true for multiple head printing systems.
It was previously considered that low-cost encoders could not be used for systems requiring extremely high precision. Instead, if high precision was needed, more precise (and expensive) encoders had to be used. A particularly accurate known encoder is a Teledyne-Gurley encoder. However, such an encoder costs approximately $1000. In one particular drum architecture, it is desirable to have an encoder runout of about 0.5 mRad. However, conventional low-cost encoders typically have a runout error of about 3.0 mRad. As such, one would not expect that a low-cost encoder could work with an architecture having such high accuracy requirements. While a Teledyne-Gurley encoder would be suitable for such an application, it greatly increases the cost of the architecture.